Wednesday, May 15, 2013

New paper finds recent solar minimum associated with the largest recorded increase in Galactic Cosmic Rays

A paper published today in Advances in Space Research finds "The evidently low solar activity observed between solar cycles 23 and 24 during the years 2008-2010 led to a substantial increase in the Galactic Cosmic Ray (GCR) intensity in comparison to preceding solar minima" and that "the Galactic Cosmic Ray exposure during the recent solar minimum was indeed the largest in comparison with previous minima." Galactic Cosmic Rays are thought to be an amplifying mechanism of solar activity by forming more clouds when solar activity is low, and vice versa [the Svensmark theory of cosmoclimatology].

The evidently low solar activity observed between solar cycles 23 and 24 during the years 2008-2010 led to a substantial increase in the Galactic Cosmic Ray (GCR) intensity in comparison to preceding solar minima. As the GCRs consist of highly-ionizing charged particles having the potential to cause biological damage, they are a subject of concern for manned missions to space. With the enhanced particle fluxes observed between 2008 and 2010, it is reasonable to assume that the radiation exposure from GCR must have also increased to unusually high levels. In this paper, the GCR exposure outside and inside the Earth’s magnetosphere is numerically calculated for time periods starting from 1970 to the end of 2011 in order to investigate the increase in dose levels during the years 2008-2010 in comparison with the last three solar minima. The dose rates were calculated in a water sphere, used as a surrogate for the human body, either unshielded or surrounded by aluminium shielding of 0.3, 10 or 40 g/cm2. On performing such a long-term analysis, it was estimated that the GCR exposure during the recent solar minimum was indeed the largest in comparison with previous minima and that the increase was more pronounced for locations outside the magnetosphere.